This manual covers the YSE Series marine diesel engines, specifically the YSE8 and YSE12 variants. These engines are recognized for their robust construction and reliable performance, making them a trusted choice for various marine applications. Engineered for durability and efficiency, the YSE series embodies a commitment to quality in marine propulsion. Their compact design and straightforward operation ensure they meet the demanding requirements of boat owners and operators. This comprehensive workshop manual provides essential information for the maintenance, servicing, and repair of your YSE Series engine. It includes detailed procedures for routine maintenance tasks, troubleshooting common issues, and in-depth repair instructions. With clear, step-by-step guidance, supported by pictures and wiring diagrams, this manual is an indispensable resource for owners, mechanics, and technicians to ensure optimal engine performance and longevity.